There are various kinds of mouse devices used as input devices for computers. Among those, optical mouse devices are widely used due to their intuitive usability for users. An optical mouse emits light from its bottom, senses the light reflected back from an object such as a desk with a built-in optical sensor, and sends the sensed data to a computer. The optical mouse also detects a click operation performed on a click button on the upper front surface or a side surface of the mouse, and sends the detected data to the computer. Through these operations, the user can move a pointer and select a menu on a display screen of the computer, for example.
Computers are now used in various places. With the use of computers expanding, mouse as input device for those computers are required to have properties suited for their usage conditions. For example, there are needs for mouse that can be used in wet places using water like on board a ship, in kitchens, or in bathrooms and the like. A mouse accommodates a light-emitting device such as an LED, an optical sensor such as an image sensor and an optical coupler, a signal processing IC, a resistive element, and other electronic circuits. These electronic components are susceptive to humidity. If some moisture enters a mouse, the electronic circuits may be damaged, resulting in the failure of the mouse.
There are needs for mouse devices that can be used in clean places requiring hygiene like in operating rooms or in workplaces for processing meat or fish, for operating personal computers. In recent years, in cardiac catheter operations, mouse has been used for handling CT data in a similar way to handling CADCAM data in the industrial field. In the dental field, which has also adopted CT scanning, mouse has increasingly been used during dental treatments for manipulating computers in order to visually check the CT image data of target sites on computer screens by switching screens, moving view points on the image data, enlarging the image data while proceeding the treatments. When a mouse is used in treatment room or operating room, the mouse should be sterilized for infection control. For example, it is effective to perform autoclave sterilization (high-pressure steam sterilization) at a pressure in the range of 2 to 2.2 atm, at a temperature in the range of 121 to 135° C., and for approximately 20 minutes. The possibility of damaging mouse substantially, however, makes it difficult to perform such sterilization on mouse.
Japanese Patent Application Laid-Open No. 9-319515 (Patent Literature 1) discloses an invention related to a mouse. Patent Literature 1 describes a mouse for a computer including an upper mouse casing made of an antibacterial synthetic resin that is touched by a user operating a button by hand.